The present invention relates generally to mounted crop harvesting machines having a hydraulically driven crop gathering header and, more particularly, to a means for converting the header lift cylinders from a double-acting mode to a single-acting mode to facilitate a mounting of the implement frame to a tractor.
Mounted harvesting implements, as opposed to pull-type harvesters which are connected to a tractor and towed behind, are affixed to and supported from the tractor to be pushed or pulled into the crop material to be harvested. With the advent of a hydraulically powered, articulated, tractor, such as the Model 276 Bidirectional.TM. tractor manufactured by Ford New Holland, Inc., harvesting implements can be both mounted and towed for simultaneous operation in the harvesting of the crop material.
Implements have been mounted on such tractors by the engagement of a pair of transversely spaced mounting arms with corresponding support members and attachment brackets affixed to the tractor. Manipulating the orientation of the mounting arms on the harvesting implement for proper alignment with the tractor is a problem which can be resolved with the utilization of double-acting hydraulic cylinders controlling the articulation of the implement frame to vary the orientation of the mounting arms to effect proper alignment with the attachment brackets carried by the tractor. However, double-acting hydraulic cylinders are not conducive to proper operation of the harvesting implement due to flotational characteristics desired for the crop gathering header and the need to prevent hydraulic pressure from driving the crop gathering header into the ground.